务正道铝土矿基底古地貌与矿石品质的关系——以务川大竹园铝土矿床为例

Relationship Between Basal Paleogeomorphology and Bauxite Ore Quality in the Wuchuan-Zheng'an-Daozhen Area: An Example From the Dazhuyuan Bauxite Ore Deposit

本文以贵州务正道地区务川大竹园铝土矿床为例,对其岩相古地理进行总结,并对基底古地貌与铝土矿品质的关系进行分析。研究认为,务正道铝土矿受沉积环境的制约,呈环状分布于滨湖相、三角洲相和浅湖相的沉积环境中,其中以浅湖相环境下形成的铝土矿质量较优,而滨湖相和三角洲相环境下形成的铝土矿则质量欠佳。铝土矿含矿岩系赋存在基底页岩或碳酸盐岩准平原化地貌之上,铝土矿的品质不仅受物源供给、沉积环境的制约,而且还与准平原化地貌特征密切相关,在基底古地貌低凹处三氧化二铝含量较高,铝硅比值较大;基底古地形地貌即坑洼形态、大小、深度控制了铝土矿体的展布范围、产出形态、贫富变化及其形成规模。

Taking the Dazhuyuan bauxite ore deposit in the Wuchuan-Zhengim-Daozhen area, Guizhou Province as an example, this paper studies the lithofacies and paleogeography and the relationship between basal palaeogeomorphology and bauxite ore quality. The bauxite ores in the Wuchuan-Zheng＇an-Daozhen area are controlled by the sedimentary environment, and are distributed in lakeshore facies, delta facies and shallow lacustrine environments. The bauxite ore quality from the shallow lacustrine environment is the best, and that from the lakeshore facies, delta facies follows. The ore-beating rock series occurs on the geomorphology of basal shale or carbonate peneplain, and the bauxite ore quality is controlled by material supply and the sedimentary environment, and is also closely related to the geomorphological characteristics of the peneplain. In the low areas of ancient landforms of the basement, the content of Al2O3 is high, with high Al-Si ratios. The ancient basement terrain, including pit form, size and its depth, exerts a key control on the distribu- tion, occurrence, grade and scale of the bauxite orebodies.